IN boost
MODE (MODE 1), WHEN
THE SWITCH S1 IS ON AND S2 IS OFF,
VOLTAGE ACROSS THE INDUCTOR

VL
=2 VIN - VOUT

VL
=2* 12V- 18V

VL
=6V

FOR AN
INDUCTOR VOLTAGE CURRENT BASIC RELATION IS

VL =
L * dI / dt

THEN,
L = VL * dt / dI

L = VL * dt / dI

HERE dt = DUTY CYCLE /
FREQUENCY

Assume that operating frequency of the switch (mosfet
here) =195 kHz

AND dI IS THE RIPPLE
CURRENT OF INDUCTOR

IL = IIN= 4.16A

From
the industrial viewpoint,the output inductor is generally designed to have no
negative current when the output current is above 20%~40% of the rated output
current . Therefore, in this paper, the boundary between the positive current
and the negative current is assumed to be at 40% of the rated output current.
Hence, the

value
of Lo can be obtained as follows:

Assume that inductor ripple current = 30% of inductor current

dI =40% * IL

dI =40% * 4.16A *2

dI = 3.328 A

L = VL * dt / dI

L = VL *
D / (F * di)

L = 6V * 0.5 / (195000 Hz * 3.328 A)

L = 4.6uH

CHARGE
PUMP CAPACITOR VALUE

FOR A CAPACITOR VOLTAGE
CURRENT BASIC RELATION IS

I = C * dV / dt

dV is output ripple voltage. Assume that output ripple
voltage is about 0.05% of output voltage

dV = 0.1% * 12V

dV = 0.012V

C = IIN * dt / dV

We have dt = duty ratio/frequency

C = IIN * D / (F * dV )

C = 4.16A * 0.5/ (195000 Hz* 0.012 V)

C =888uF =1000 uF (standard value)

CHARGE
PUMP CAPACITOR VALUE

FOR A CAPACITOR VOLTAGE
CURRENT BASIC RELATION IS

I = C * dV / dt

dV is output ripple voltage. Assume that output ripple
voltage is about 0.05% of output voltage